Japanese Examined Utility Model Application Publication No. 4-39747 (Patent Literature 1) relates to the above-described technical field. The seat disclosed in the publication includes a foamed cushion member molded into a seat shape, a bag-like covering body fixed to the cushion member side so as to be covered, a first cover for covering the front surface side of the covering body, a second cover for covering the rear side of the covering body, and a slide fastener for connecting the first and the second covers. The sense of foreign matter felt by the seated occupant may be eliminated by disposing the slide fastener onto the side surface of the seat back.